Case IH 19213 – Engine Control Module (ECM) / Engine Control Unit (ECU): Lambda value is greater than NOx monitoring soft threshold of lambda value

The engine's lambda sensor is reading a value that exceeds the programmed soft limit required for the Selective Catalytic Reduction (SCR) system to accurately monitor and reduce Nitrogen Oxide (NOx) emissions. This typically points to an issue with the lambda sensor itself, an exhaust/intake leak skewing the oxygen readings, or a failure in the NOx monitoring circuit.

• Tier 4b
• Puma Series
• Optum Series
• Maxxum EP Tier 4
• Farmall C Series
• Axial-Flow Combines (7250/8050/9250)
• WD2505 Windrowers

1. 1

   Check the Lambda sensor and NOx sensor wiring harnesses for damage, specifically looking for open circuits at the Lambda sensor pins (Nearest cell pin, Pump Current Pin, Virtual Ground Pin) and the LSU Heater Power stage.

2. 2

   Inspect the exhaust system (especially around the DPF/SCR chamber) and intake manifold for leaks that could introduce unmetered air and skew the lambda readings.

3. 3

   Verify that the SCR chamber is reaching operating temperature (240.0 °C / 464.0 °F) and that the DEF dosing module is injecting urea properly, as NOx sensors rely on this to calculate emissions.

4. 4

   Use a dealer-level diagnostic tool to read freeze frame data and verify if the upstream or downstream NOx sensors are also throwing plausibility codes.

1. 1

   Power Down

   Turn off the machine and disconnect the battery to prevent electrical shorts and allow the exhaust system to cool down.

2. 2

   Locate the Sensors

   Locate the Lambda sensor and the NOx sensor(s) in the exhaust stream, typically mounted near the DPF/SCR aftertreatment chamber.

3. 3

   Remove the Faulty Sensor

   Disconnect the electrical connector from the Lambda sensor (or NOx sensor, depending on diagnostic results). Carefully unscrew the sensor from the exhaust pipe.

4. 4

   Install the New Sensor

   Thread the new sensor into the exhaust bung. (Note: OEM replacement sensors often come with pre-greased M18x1.5 threads). Tighten to the manufacturer's specified torque and reconnect the wiring harness.

5. 5

   ECU Reset and Calibration

   Reconnect the battery. Connect a diagnostic tool to the machine's diagnostic port.

6. 6

   Clear Codes and Reset Counters

   Clear fault code 19213. You must perform a 'Reset ECU data (Lambda sensor)' procedure. If the machine entered a torque/RPM derate mode, perform a 'Startup counter reset' / inducement mode reset to restore full engine power.